# Crosshead Ø8 × 24 for a Ø3 piston rod

> What are the dimensions of a crosshead for a small Stirling engine piston rod?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Ø8 slider in the Ø8 guide (fit: run); clevis slot at the 5 mm con-rod thickness
- Page: https://xemstudio.com/objects/crosshead-8mm/ · JSON: https://xemstudio.com/api/geometry?object=crosshead-8mm · Plain text: https://xemstudio.com/objects/crosshead-8mm/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- A Ø8 × 24 slider on the Ø3 piston rod (Ø3 bore, fit: slide) that runs in the Ø8 crosshead guide (fit: run).
- A 5 mm slot, 13 deep, takes the 5 mm con-rod end (fit: run); a Ø3 hole through both cheeks 5 mm from the top takes the wrist pin (fit: press).
- The con-rod's sideways push lands on the crosshead and guide, so the piston moves only along its axis.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| crosshead OD | Ø8 | crosshead-guide bore (slides in it) | run | crosshead-8mm* |
| crosshead rod bore | Ø3 | Ø3 piston rod | slide | crosshead-8mm* |
| crosshead clevis slot | 5 | 5 mm con-rod end | run | crosshead-8mm* |
| crosshead wrist-pin hole | Ø3 | wrist-pin-3x16 | press | crosshead-8mm* |

## Sizes

| parameter | value |
|---|---|
| slider | Ø8 × 24 |
| rod bore | Ø3 |
| clevis slot | 5 × 10 deep |
| wrist-pin hole | Ø3, 5 from top |

## Where the files are

- Wikipedia: [Crosshead](https://en.wikipedia.org/wiki/Crosshead) — web — CC BY-SA 4.0 (text)
- Wikipedia: [Piston](https://en.wikipedia.org/wiki/Piston) — web — CC BY-SA 4.0 (text)
- James R. Senft: [Miniature Stirling engine piston fits (LTD book)](https://www.stirlingengine.com/) — book — reference (verify at link)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/crosshead-8mm/index.json

- crosshead-8mm-rod3: [STEP](https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/crosshead-8mm-rod3.step) · [STL](https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/crosshead-8mm-rod3.stl) — crosshead: Ø8 × 24 slider on a Ø3 piston rod, 5 mm clevis slot 13 deep for the con-rod (floor 8 below the pin) and a Ø3 wrist-pin hole 5 below the top (keeps side load off the piston)

## How it fits

### Goes in or on
- [Crosshead guide, Ø8 bore × 30](https://xemstudio.com/objects/crosshead-guide-8mm/): runs in the Ø8 bore

### Connects to
- [Wrist pin Ø3 × 16](https://xemstudio.com/objects/wrist-pin-3x16/): pin through the cheeks
- [Crank discs for a Ø5 shaft, 10 to 30 mm stroke](https://xemstudio.com/objects/crank-discs-5mm-bore/): 5 mm con-rod in the slot
- [Power piston Ø16, 20, 25, 30 with Ø3 wrist-pin boss](https://xemstudio.com/objects/power-piston/): Ø3 piston rod

## Questions

**Why use a crosshead on a Stirling engine?**

It takes the con-rod's side load so the piston only moves axially and keeps its seal round.

**What con-rod fits the crosshead?**

One 5 mm thick, in the 5 mm clevis slot on a Ø3 wrist pin.

## Fits with

- [Crosshead guide, Ø8 bore × 30](https://xemstudio.com/objects/crosshead-guide-8mm/)
- [Wrist pin Ø3 × 16](https://xemstudio.com/objects/wrist-pin-3x16/)
- [Power piston Ø16, 20, 25, 30 with Ø3 wrist-pin boss](https://xemstudio.com/objects/power-piston/)
- [Crank discs for a Ø5 shaft, 10 to 30 mm stroke](https://xemstudio.com/objects/crank-discs-5mm-bore/)